Unit type filter



GRIFFITHS UNIT TYPE FILTER Filed Sept. 15, 1945 6 Sheets-Sheet 1INVENTOR ATTO RN EY;

5 J. GRIFFITHS UNIT TYPE FILTER July 8, 1952 6 Sheets-Sheet 2 FiledSept. 13, 1945 5 J. GRIFFITHS UNIT TYPE FILTER July 8, 1 952 6Sheets-Sheet 3 Filed Sept. 13, 1945 INVENTOR ATTORNEY:

July 8, 1952 E. J. GRIFFITHS 2,602,548

UNIT TYPE FILTER Filed Sept. 15, 1945 6 Sheets-Sheet 4 IN V EN TOR.

July 8, 1952 Filed Sept. 15, 1945 E. J. GRIFFITHS 42,602,548

UNIT TYPE FILTER 6 Sheets-Sheet 5 HI l MB 0 9 'gfl 0 Q o o o 9 o o o o ao 0 Q 0 0 0 o o o o 0 o o o o o o q I a o o o 0 0 o 0 0 V0;

0 o e o o 0 o o 0 l allllilllllllll w o o o o o o G) 0 INVENTOR.

W \WM July 8, 1952 v E. J. GRIFFITHS 2,602,543

' UNIT TYPE FILTER I Filed Sept. 13, 1945 v e Sheets-Sheet e IN V ENTOR.

Patented July 8 1952 j UNITED IsTAT s PATENT pore-reef V ApplicationSeptember 1' This invention relates to gfilters and especially tofilters of the type in which a number of plates aresecured together toform a unitistructure with filter elements secured betweenthe plates.Such filters are made with; fasteningmeans that are easily releasablefor dismantling the stack of plates so that the filter elements, usuallydiscs or pads, canbereplaced, V I I One-object ofthis inventi nisto'provide an improved construction forfilterscf the characterdescribedq More specific objects .areto widenthe field ,to whichsuch;'filters;are applicable, to reduce the cost of such filters byproviding constructions that do not requiresuch close manufacturingtolerances, and to improve the. efficiency of such filters byprovidinginlet openings that promote circulation of the fluid over the filterpads. i a

Filters made up of stacks of plates with pads held between them havebeen used in the dairy, food, soft'drink, and other industries where itis necessary, to have afilter that can be dismantled conveniently andcompletely for thorough cleaning. Such filters have required plates madewith close tolerances inorder to clamp the filter element evenly andpreventfleaks and Icy-passing, and-the plates have had to .behandled-carefully to prevent denting orbending which would destroys-the.even clamping; pressure around the edges; This invention increases thefield. of application; for filters of the general type referred to .byproviding constructions. in which; resilient platesgare usedtdclampthefilter elements or pad s and in which. the pressureior clampihg is taiedty r i on el m n a vea d belqw hetac fp esuc 'acons ucti 13, 1945;Serial No; 615,964

1 Claim. (01, 21o170) permits theiuse: .of' plates-that are. lighter,inade of different m'aterial than formerl ilessliable to be dentedinhandling, and adaptd to clamp the pads evenly. without such closemanuiacturing tolerances because the. stifiness of the. plates is not:relied upon to produce theclaniping pressure. 4:

This invention widensthe field of; application of filters of thecharacter indicated, to" the field of air and. gasfilters, and filtersfor oil and vari- Another object .of the'invention'is 'to provideastack-type filter in which plates surrounding a standpipe can beclamped together by cam means that eliminate the use of screw threads.With dairy filters that require very thorough cleaning this constructionparticularly advantageous because screw threads are difiicult to. cleanto the high standard required in a dairy filter.

Other objects relateto the construction of the plates used in stack-typefilters for clamping the pads or discs. One feature relates to a plateconstruction that obtains; a decreasing cross section, in the directionof fluid flow, o f the 'space' between the plate and the side of thefilter pad from which the fluid flows through the pad, and a crosssection of increasing area between the other side of the pad and thenext plate below. Such a construction increases the capacity of thefilter for a given height because it permits the plates to be positionedcloser together without increasing thepr'essure drop through the filter.This is made possible by the fact that the cross sections of the spacesthrough which the fluid flows are approximately proportional tothevolume of fluid at the difierent regions above. and below the filterpad.

Another feature relates to a construction in which-pressed metal platesare ,formedso as to partially nest for-centering them with respect toone another. -.The inventionobtains this centering effect while.maintaining a construction thatprovides for adequate clamping of theinner and outer edgesofthe filterpads."

Several modificationsv of. the invention provide different means forholding the filter pads spaced from the'body. portionsgof" the platesbetween which the filter pads are clamped. These spaca ing meanspermit'flowof fluid, especially liquid,

the filter.

ous other fluids and also where'it is advantageous to'reduce velocitythrough the filter by providing largea'reas over which the filt'eri'ngof the fiuidis'distributed. I i1 50 Otherfeaturesof theinventi'on relatetoa con the funnel; the

Otherobjects, features and'advantages of the invention will appear forbe pointed out as the specification proceeds; a 1

In thedrawings, forming apart hereof; in which like reference charactersindicate corresponding parts mall the views,

. Figure 1 is a vertical sectional view through a funnel with affilterunit of this invention'in'position for filtering theliquid that flowsthrough filter-innit being shown .in 'eleo -1, a i

Figure 2 is anenlarged, fragmentary, sectional view through a portion ofthej'lfilte'r unit shown inFigurel.

Figure 3' is a vertical sectional .view' showing a modified form ofthetfilterunitbf thisinvention connectedjwitn a flexib e hose and,inserted iiht'o a vessel from which liquid is to be withdrawn by suctionpump, syphon or vacuum.

Figure 4 is a sectional view through a sump of a crankcase with thefilter unit of; this invention employedl'as an 'oiYfiI'ter.

Figure 5 is an enlarged view, mostly in section, of a filter unitembodying this invention. k Figure 6 is a detail view taken on the line5- 5 of Figure 5.

Figure '7 is a reduced, sectional view taken on the line 1( of Figure 5.I 'f Figure 8 is a reduced top plan View of one of the filter plates ofthe units shown in Figures 1-5.

Figure 9 is a fragmentary side elevation of the outside rim of a filterplate with a modified form of opening for admitting fluid into thefilter unit. 1 V 7 Figure 10 isa' sectional view l0 -l0 of Figure 9.

Figure 11 is a sectional view taken on the lin H-Il of Figure 10. I

Figure 12'is a side elevation, partly in section, showing amodified formof filter with'the plates clamped" together without the use of screwthreads.

taken on the line Figure 13' is a sectional view taken onthe line Figure21 is an enlarged sectional view, partly broken away, showing anothermodified form of plate construction in which the plates nest for thepurpose of aligning themwith one another.

Figure 23 is a reduced scalejtop plan View of another modified form .ofthe invention in which both the inner and outerrims of the plate areformed-so as to nest with the next'adjacent plate. -Figure 22 isanenlarged-sectional view'taken on the line 22'-'22 of Figure 23, part ofthe intermediate structure of -the body portion beingbroken out inorder-lto increase the scale of the drawing.

Figure 1 showsa funnellS that is of circular cross section and that hasa tapered side wall I5 connected at its lower edge with the dischargeend or point I! of the funnel. The discharge end I! is of cylindricalform in Figure 1, but in funnel constructions this point portion issometimes tapered, and may be corrugated. A filter unit [9 comprises arigid disc or top plate 20 and another rigid disc or bottom plate2lbetween which there are a number of filter plates 22. The plates 20 and2| are held together by tension elements comprising stud bolts 24,. 1

I There is a pipe atrthe-center of. the plate '21 comprising an outletconnection 26 which is preferably an integral part of the plate 2 I.Within. the opening through the .pipe, orputlet 26 there are bosses withthreaded openings for receiving the stud bolts as willbe explainediullyin connection with Figure 5.

lower outside corner of the bottom plate 2| is recessed and contains aninsert or packing ring This ring 30 is made of rubber, or otherpacking-material that is soft enough to be deformed by the weight of thefilter unit 19 so that the ring 39 forms a liquid tight seal between thefilter unit I9 and the sloping side wall I6 of the funnel. When thefilter unit I9 is to be used with the funnel l5, therefore, it issufficient to merely place the filter unit [9 in the funnel without anyconnections between the filter unit and the funnel. As more liquid ispoured into the upper end of the funnel, the pressure deforming thesealing ring 30 becomes greater and the seal becomes tighter.

Fluid enters the filter unit through angularly spaced openings 32 in theoutside rims of the filter plates 22. *There is a filtering elementorpad 34, preferably cloth, clamped between-each of the filter plates 22and its adjoining plate. Fluid entering the filter unit through theopenngs 32 flows through the filter pads 34 and out into a centralopening in the filter,as will be explained more fully in connection withFigure 5. Liquid 35 placed in the funnel I5 flows through the filterunit Iii-and discharges-as a stream 35' through the outlet'connection26.

' Figure 3 shows a filter "unit 31 that is of similar construction tothe unit l9 of Figure 1 except that it has upper and lower rigid plates38 and 39 that extend beyond the filter plates 22 and are clampedtogether-by tension elements comprising bolts 4| that fit into notches42- (Figure 7 in the rigid backing-up plates Hand 39. The bolts 4| areprovided with wingnuts '43-for clampingthe backing-up plates together.

The filter unit 31 of Figure-3 has its outlet connection 26 connectedwith a fitting 45 'on the s end of a fiexiblehose 45. The flexible hoseconnects with an inlet 41 ofa pump. which discharges fiuid to a conduit49.- The filter unit-'31 is shown immersed'in liquid 51 in a-tank orvessel 52 from which the liquid is to be drawn by the pump 48 or othermeans: The filter unit31,

being connected 'with'a flexible hose 4'5, can-be inserted into anyreservoir or vessel from which liquid is to be pumped, and all liquiddrawn into the pump 48 and dischargedfinto the conduit49 will befiltere'd liquidreg'ardless of the reservoir or tank from which itcomes.- The filter unit 31,

with'pads o'f'proper mesh for the purpose, can be Figures 1 and 2 but--without[ any sealing ring 30 has itsoutlet connectionifi'extendingthrough the cover plate 51'and-heldin place by clamping nuts 69 'with'wa'shers"6I "for insuring a liquid Y tight *seal. The filterpun'it' 59ispi asli'ghtly smaller section'than the sump'ijnj which it is locatedso that there is space foroilfaround the plates, flows through thefilterunit 59, and out 1, the plates 20"an'd2l are of substantially: the

same diameter as the filter plates 22 and the throughthe connectionf26which connects with piping 53 that leads to anfoilpumpl forrecirculating thefoil toan engine or other apparatus abovethecrankcase'54. U

f Figure 5 is an enlargedview showing the inside constructionof the 'filterf,unit 3 .l' of Figure}. Each of the filter plates 22 has an'outside rim 61 and an inner rim 88. .The body portionof the...

for the filter elements 34, as shown in Figure 5.

The outside rims-61 of the filter plates extend downward, and the innerrims 88 extend upward, but theseinner and outer rims are preferably ofthe :same height, and the body portion of the filter plate isconstructed so that the upper edges of the rims 67 and 680i each plateare on substantially the same level. v v

The filter elements 34 are of slightly larger diameter than the filterplates 22 and there is a central opening through each of the filterelements 34 of slightly smaller diameter-than the cylindrical spaceenclosed by the inner rim 68 of each of the filter plates. When a filterelement 34 is placed between two of the filter plates 22, with its axiscoincident with theaxis of the filter plates, and the plates are clampedtogether, the edges of the filter element 34 are firmly held between theadjacent outer rims 8! and inner rims 68 of the filter plates 22.

Fluid which enters the openings 32 flows across the top surface of thefilter element 34, passes downward through the filter element,'and'thro'ugh the spaces between the corrugations 18 of the plate thatsupports the filter element 34. The

fluid flows out through the openings 12 in therim 88 and into thechamber enclosed by the inner rims 68. The bottom backing-up plate 39closes the lower end of the chamber at the center portion'of the filter,but the outlet connection 28 opens through the upper plate 38 andpermits the fluid to flow out of the filter unit.

It is important that each of the filter elements 34 be clamped securelyaround both its inner andouter edges when the filter element 34 is madeof cloth, or other material that can'be deformed downward intothe-spaces between corrugations 10, when the pressure forcing the fiuidthrough the filter elements is of a considerable magnitude. If a'clothfilter element is not firmly clampedaround its edges, and does pullinward because of excessive sag into the spacesibetween the corrugations18, there is a leak created between the portions of the adjacent filterplates from which'the filter element pulls away. -'One of the advantagesof this invention'is that the backing-up plates 38 and 33 apply pressureto both the inner and outer rims of the filter plates.

audit is not necessary, that the filter plates themselves havesufficient stiffness to clamp the the application of high clampingpressureto the inner and-outer rims of the filter plates for holding thefilter elements in place in filter units that operate under highpressure. This con'-' struction also permits the use-of lighterbackingup plates 38 and 39." It isusually suflici'ent, how ever, to haveonly the center tension -elements 24' and-nuts '|4'-forholding thefilter unit in assembled relation, and with such construction; the:extending rim portions on the backing-up; plates 38 and 39 withnotchesion receiving the bolts 4| are not-necessary; The 'discs thatcom- 0f filter plates 8l'surround a standpipe 82.

filter plates. The filter elements. I9 and 59, illustratedlinFiguresil.and 4, res'pectively, do not have extended; backingrup-i plates .orperipheral clamping bolts;4|.. ,In. the preferred embodiment:oftheinventionthere are three tensionv elements 24, this being the fewestthat will center thee-filter plates, and .these tension elements arelocated so.that theyare-stangent to a.v circle that is substantiallyequal. in radiusto the. center openings through the filter plates. r

The filter unit can be made with clampin bolts 4| around its outsideedge, and without any center clamping means such as the tension ele-"ments 24 and nuts 14. Constructions without the center clamping meansprovide a larger section of conduit for the discharge of liquid from thecenter portion of the filter unit.

In order to distribute the incoming fluid more evenly over the surfaceof the filter elements, the openings 32 in the outer rims 81 of thefilter plates are provided with vanes 16. These vanes deflect theincoming fluid and tend to make it follow a spiral course toward thecenter of the filter unit. Two different constructions for the inletopenings are shown in the drawing; The

openings 32, illustrated in Figures 1 to 5' and 8,

. no metal is removed and all of the metal displace from the opening isused as the vane 15, the construction being well illustrated in Figure8.

Figures 9 to 11 show another form of opening in which metal is removedfrom the outer flange 81 by punching an opening, preferably a circularopening 18, through the flange of the filter plate. The metal at oneside of the opening 18 is then bent inward to form a corrugation 19 thatserves as the vane. to produce a generally spiral direction of fluidflow into the filter.

Figure 12 shows a construction in which a stack A rigid plate 84, underthe bottom filter plate 8|, rests on a shouldered fitting 85 at thelower end of the standpipe 82.

' The plates are clamped by a collar 86 that fits freely over the upperend of the standpipe and that has a cam surface 81 on its top face. Thiscam surface 81 reacts against a plug fitting with a stud 88 thereon.This stud extends through the side of the standpipe. The stud 88 can be1 designed to extend through the standpipe on both sides, and thecamface 81 can be made with two inclinedsections for cooperation with sucha pin 88 extending through both sides of the standpipe.

In the preferred construction, illustrated in Figure 12, the stud 88extends through only one side of the standpipe and the cam face 81 is asingle slope around the entire circumference of the top face of thecollar 86. This construction has the advantage that it obtains a largercam throw with a slope that is gradual enough to make the cam meansirreversible. The collar 88 is of non-circular cross section, ahexagonal shape'being shown in the drawing, or flats on the sides of thecollar can be provided, so that the collar can be rotated by a wrench ora special tool. As the collar 86 turns in one direction the cam face 81forces the collar downward against a rigid plate 98 that covers the topfilter plate 8| and clamps the filter plates firmly togeth'erraTheincline of thegcamliface, 81.;isso;

gradual that friction {of ..:the..-pin .88.: against; the cam face. is.sufficient tol cause thercollari 86; to remain in:.any clamped.positionu 1.

' In the, construction illustrated, thelst' d 88 ex:

tendsirom the; sides of. a;.plug; 92. which closes the upper end ofthestandpipel 82 and. is held in place by bayonet type slot 93in the upperend of the .standpipe. ,This bayonet. type slot 93 has.

rest stopsat its-end so that thestud-BB can resist ;the thrust ot thecam .face. 81... without danger of displacing-the stud 88 in the slot..93. The reason for having ,theplug 192 removable is to'make itpossibletoclea-n the-inside ,of the standpipe more easily by avoidinginaccessible corners 'such as; would begpresentingthe upper end of ,the'standpipe, if ,the plug 592 were not removable.- All,',ofg t heclamping elements:,-in cluding the collan; pin ,88 and plug -92 areeasily cleaned when; the filter is disassembled.

The filter plates iii are of a diiierent construction fromthoseillustrated-in the; previous views of the drawing. This modified plateconstruction includes a two piececonstruction in which there is a lowerplate element '95 with an inner flange 96 and outer flange; 9;? Thefilter pads 34 are clamped between ;these flanges and the corr spondinflan s of th nex fi t r plat ov and below in;the .same manner as in VFigure;

The lower mateel ent 55 in E gumil is ne p wit an ridse to s p rtin efil r p ';ln-pl e o es. a p errl element 98 is m loy d Thi upper plat elen s pe o d an ss a edqtonfit the wer lat element 95in sueh a way t hatit is held in place by t least one, ende erabl both i t flanges of thelowerplate element; n

- There are openings I00; in the clown-turned outer flange 97, andopenings IOI'in the upturned inner flange 96 "for passage of-fluid toand from the spaces above and below the'filterpa d. The upper plateelement 98 is made withas much open area as possible while maintainingthe necessary strength forthis upper plate element 98 which must supportthe filter pad against the pressure head required to force fluid throughthe pad at a predetermined rate. In the construction shown in Figure 12,the upper plate element;98 has down-turned flanges by which it issupported from the lower plate element "at, and the inner of theseflanges is provided "with openings I03 for passage of fluid. Figureshows'a construction in which filter plates I05 have outer flangesflanges Iil'i, but have these flanges connected-by a bodyportion I08which slopes in such a way that the space above'and below the filter pad34- changes, in cross section in proportion to the change in the volumeof the fluid passing through the space. For example, all of the fluidflowing into the spaceabove the-filter 34 passes over the area of thefilter immediately adjacent theflangeII36.- As the fluid moves radiallyinward, some ofit passes down through the filter pad 34, so thatthevolume of the fluid in the space between the filter .pad 34 and theunder side of. the upper plate I05 decreasesprogressively Conversely,the volume offluid under the pad 3 becomes greater and greater as thefluid under the padinoves toward the inner flange Iii'I. arcuate ridgesI'Iilformed in the body portions I08 of the plates IE5; and these ridgesII!) are of different heights along the sloping-surface of the filterplates lfl5- so that the pad "34 which l 65 and inner There are 1 issupported. by theridges II 0 is maintained sub; stantially. level. Theadvantage of this COIlStIllC-r tion is thatv the space betweenthe-filter plates. I05 can be made smaller without'increasing. thepressure dropas compared with filters thatdo not=haveIa varyingcrosssection. The ridges, I Illv are made with a buttress section instead oftheuround section shown in Figure 5. The purpose, of, this buttresssection, in the filter plates Hi5 of Figure 15 .is to obtain a sharperridge. ,When the filter plates-are in use there is some sagging of thefilter pads 34 across the space between the supporting ridges III] andthe area of the filter pad through, whichliquid can'pass is reducedbycontact of the filter pad with the surfaces of the supporting ridges; Byhaving the supporting ridges shaped so that they are sharper at theirupper ends, less area of the filter padis rendered ineffective by anygiven amount of sagging of the pad. On the other hand thereis a limithow'sharp the ridges can be made if the plates are to be pressed. Thebuttress construction shown in Figure 15 is advantageous because itobtains acornparatively sharp ridge and still provides a shape suitablefor.

Figure 16 shows a planyiew of one of the plates I of Figure 15. RidgesIIl'I are in such relation to one another that there are radial passagesbetween adjacent ends of the diiierent ridge sections 1 I8 from theperiphery of the plate to the center opening. This construction permitsa freer flow of liquid across the face of the platethan does thestaggeredridge construction of Figure 8, and provides enough support forthe filter pad if the pressure at which the filter operates is not toohigh.

Another plate construction'for reducing the obstruction to liquid flowis shown in Figure 1'7. This figure shows a plate H4 with spiral ridgesH5 that hold the filter pad away from the body of the plate withoutobstructing the radial flow of the liquid toward the center opening. Inorder to provide for better distribution of the liquid across the areaof the filter pad, the ridges N5 of Figure 17 are given a slight spiralpitch. This type of plate is useful for filters that operate Figure 18shows another modified plate construction in whichva plate II'I isprovided with a plurality of nodules II8 that hold the filter pad spacedfrom thebody of the plate at a multitude of spaced:locations,over thearea of the plate. j

Figure 21 shows a specialtype-of plate construction in which the innerrims of the plates nest so that the filter assembly requires nostandpipe; "In thisconstruction each of the platesI2I has a bodyportionI22 in which there are supporting ridges I23 for holding the filter pad34 spaced from the body portion of the plate. The plate I2I has aperipheral portion including a face I25 and a downturned rim I26 thatclamps the filter pad 34 against the face I25 of the next The novelconstruction of each of the filter plates I2I is at the inner portionaround the central opening through the filter plate. The

inner portion of the body I22 extends down to 'a level approximately thesame as that of the lower end of the rim I26, and then turns upward toform an inner rim I30 that slopes outward away from the central axis ofthe plate. The inner rim I30 has openings I3I for the fiow of fluid intothe central opening through the filter plates.

The inner rim I30 extends upward and then turns inward at approximatelythe level of the face I25 to form a clamping face I32 against which thefilter pad 34 is clamped by the bottom of the next filter plate above.The face I32 extends inward and merges with an upturned centering rimI33 that forms the upper end of the rim I30. The construction is suchthat the outside diameter of the centering rim I33 is approximatelyequal to, or slightly less than,'the

' center opening in the plate at the bottom level of the plate. Withthis construction any number of plates can be nested, as shown in Figure21, to obtain a filter unit in which the plates are maintained in axialalignment without the use of a standpipe. I

In order to obtain clamping pressure against liquid, but it will beunderstood that most features of the invention are equally applicable tofilters for air or other gases. Terms of orientation, such as upturnedand downturned, are, of course, relative. Parts can be reversed andvarious other changes and modifications can be made in the constructionsillustrated, and some features can be used without others withoutdeparting from the invention.

' I claim as my invention:

A filter including a stack of fiexible annular plates disposed about astandpipe, each of said plates having an inner and an outer rim forclamping filter elements between the plates, openings in the rims forpassage of liquid, said openings being at locations which place thefilter elements in parallel circuits, a shoulder at one end of thestandpipe in position to hold one of the rigid plates against the stack,a collar surrounding the other end of the standpipe be yond the otherrigid plate, said other end'of the standpipe being smooth and unthreadedand the the filter pads 34 it is necessary that the'plates I 2I be heldtogether, but such clamping pressure can be obtained'by tension membersaround the periphery of the plate assembly, as in the con- 'structionshown in Figure 5, or by a tie rod extending through the center of thestack of plates. The centering rims I33 not only serve to center therespective plates with the next plate above,

but also serve to center the filter pads 34 when they are laid on theplates during assembly'of the 'hnit. This nested construction permitsthe plates and filters to be assembled very quickly after cleaning.

Figures 22 and 23 show another modified form of the inventionconstructed in such a way that both the inner and peripheral rims of theplate nest and maintain adjacent plates centralized without the use of astandpipe or equivalent structure. Each plate has a body portion I40which preferably slopes downward toward the center, as in theconstruction shown in Figure 15, and which has supporting ridges I4I forholding the filter pad 34 out of contact with the intermediate surfaceof the body portion I40.

There is an inner rim I43 which extends upward from the body portionI40, and a peripheral rim I44 which extends downward from the outer edgeof the body portion I 40. Fluid to be filtered enters the space abovethe filter pad through openings I45 in the peripheral rim I44. Thefiltered liquid passes from the space below the filter pad 34 throughopenings I46 in the inner rim I43.

Each of the rims I 43 and I44 has an annular recess I48 in its topface-and a complementary annular ridge I49 projecting from the bottomface of the rim. The recesses I48 and the ridges I49 are shown withgenerally arcuate contour, but other shapes can be employed. The ridgesI49 nest within the recesses I48 of the next adjacent plate and pressthe edges of the filter pad 34 downward into these recesses. This notonly serves to draw the filter pad tight across the body portion of theplate, but also increase the clamping area by which the filter pad isheld.

The illustrated embodiments of the invention are shown with thefilterunits employed for collar being rotatable on the smooth'surface of thestandpipe as a bearing, the collar having a longitudinal face at one endin contact with the rigid plate at the adjacent end of the stack, andsaid collar having a sloping longitudinal face at its other end, a plugclosing the smooth interior at the end of the standpipe nearest to thecollar, a stud extending from the plug through a bayonet slot in thestandpipe, said stud extending beyond the plug for a distancesubstantially greater thanthe thickness of the standpipe wall so thatthe end portion of the plug extends beyond the smooth surface of thestandpipe and into position to provide an abutment against which thesloping surface of the collar reacts to exert an axial thrust againstthe rigid plate when the collar is rotated about the axis of thestandpipe.

- EDGAR J. GRIFFITHS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 612,105 Hendrick Oct. 11, 1898685,224 Schmidt Oct. 22, 1901 793,725 Johnson July 4, 1905 837,845Kiefer Dec. 4, 1906 984,705 Rarick Feb. 21, 1911 1,035,248 Seavey Aug.13, 1912 1,061,928 Seavey May 13, 1913 1,150,910 Warmington Aug. 24,1915 1,295,006 Corey Feb. 18, 1919 1,759,447 Fisher May 20, 19301,945,824 Saxe Feb. 6, 1934 2,059,636 Flavin et a1. Nov. 3, 19362,154,565 Fife Apr. 18, 1939 2,178,964 Hulse Nov. 7, 1939 2,278,453Kracklauer Apr. 7, 1942 2,334,448 Sheridan Nov. 16, 1943 2,345,014Stamsvik Mar. 28, 1944 2,359,475 Gauthier Oct. 3, 1944 FOREIGN PATENTSNumber Country Date 2,931 Great Britain of 1897 22,409 Great BritainNov. 6, 1901 412,100 Great Britain June 21, 1934 30,891 France (1st Add.to 608,657)

586,193 France Mar. 16, 1925

